The present invention relates to microwave antennas and, more particularly, to a telemetry and command antenna suitable for use on three-axis stabilized satellites.
The telemetry and command antennas employed on satellites heretofore have an elevation coverage angle that is too narrow. For example, the conventional end-fired dielectric rod antenna has a maximum elevation coverage angle of -90.degree. to +90.degree.. The telemetry and command antenna used on the Leasat satellite is a bicone antenna that operates in the circularly polarized mode. However, the Leasat telemetry and command bicone antenna provides only omnidirectional coverage and does not provide hemispherical coverage. The telemetry and command antenna employed on the Satellite Business Systems (SBS) satellite is also a bicone antenna but it operates only in the linearly polarized mode, and does not operate in the circularly polarized mode. Furthermore, the frequency bandwidth of conventional antennas is only about 2% of the center frequency. Typically, the telemetry and command antennas are not used both for transmitting and receiving. Instead, separate transmit and receive antennas are used.
Accordingly, it is an objective of the present invention to provide a circularlypolarized Ku-band telemetry and command bicone antenna that operates at three frequency channels. Another objective of the invention is to provide a telemetry and command bicone antenna that provides a wide elevation angle of coverage. A further objective of the present invention is to provide a bicone antenna having a hemispherical beam that is suitable for use on a three-axis stabilized satellite such as the Aussat B satellite.